Dependence of the colored frequency noise in spin torque oscillators on current and magnetic field
- School of Information and Communication Technology, KTH Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden)
- Department of Physics, Stanford University, Stanford, California 94305 (United States)
- NanOsc AB, Electrum 205, 164 40 Kista (Sweden)
- Department of Physics, University of Gothenburg, Box 100, 405 30 Gothenburg (Sweden)
The nano-scale spin torque oscillator (STO) is a compelling device for on-chip, highly tunable microwave frequency signal generation. Currently, one of the most important challenges for the STO is to increase its longer-time frequency stability by decreasing the 1/f frequency noise, but its high level makes even its measurement impossible using the phase noise mode of spectrum analyzers. Here, we present a custom made time-domain measurement system with 150 MHz measurement bandwidth making possible the investigation of the variation of the 1/f as well as the white frequency noise in a STO over a large set of operating points covering 18–25 GHz. The 1/f level is found to be highly dependent on the oscillation amplitude-frequency non-linearity and the vicinity of unexcited oscillation modes. These findings elucidate the need for a quantitative theoretical treatment of the low-frequency, colored frequency noise in STOs. Based on the results, we suggest that the 1/f frequency noise possibly can be decreased by improving the microstructural quality of the metallic thin films.
- OSTI ID:
- 22283077
- Journal Information:
- Applied Physics Letters, Vol. 104, Issue 9; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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